Chris Hayward

A study of seismic activity near Dallas/Fort Worth International Airport by researchers from SMU and UT-Austin reveals that the operation of a saltwater injection disposal well in the area was a “plausible cause” for the series of small earthquakes that occurred in the area between Oct. 30, 2008, and May 16, 2009.

The incidents under study occurred in an area of North Texas where the vast Barnett Shale geological formation traps natural gas deposits in subsurface rock.

Production in the Barnett Shale relies on the injection of pressurized water into the ground to crack open the gas-bearing rock, a process known as “hydraulic fracturing.” Some of the injected water is recovered with the produced gas in the form of waste fluids that require disposal.

A state tectonic map prepared by the Texas Bureau of Economic Geology shows a northeast-trending fault intersects the Dallas-Tarrant county line approximately at the location where the DFW quakes occurred. The study concludes, “It is plausible that the fluid injection in the southwest saltwater disposal well could have affected the in situ tectonic stress regime on the fault, reactivating it and generating the DFW earthquakes.”

The earthquakes do not appear to be directly connected to the drilling, hydraulic fracturing or gas production in the Barnett Shale, the study concludes. However, re-injection of waste fluids into a zone below the Barnett Shale at the nearby saltwater disposal well began in September 2008, seven weeks before the first DFW earthquakes occurred.

No earthquakes were recorded in the area after the injection well stopped operating in August 2009.

An SMU team led by seismologists Brian Stump and Chris Hayward placed portable, broadband seismic monitoring equipment in the area after the earthquakes began.

Stump and Hayward caution that the DFW study raises more questions than it answers.

“What we have is a correlation between seismicity, and the time and location of saltwater injection,” Stump said. “What we don’t have is complete information about the subsurface structure in the area – things like the porosity and permeability of the rock, the fluid path and how that might induce an earthquake.”

“More than 200 saltwater disposal wells are active in the area of Barnett production,” the study notes. “If the DFW earthquakes were caused by saltwater injection or other activities associated with producing gas, it is puzzling why there are only one or two areas of felt seismicity.”

Further compounding the problem, Hayward said, is that there is not a good system in place to measure the naturally occurring seismicity in Texas: “We don’t have a baseline for study.”

(Above, SMU scientists place monitoring equipment at a North Texas site. Photo by Hillsman S. Jackson.)

Scientists in SMU’s Seismology Research Program deployed monitoring stations in North Texas during summer 2009 to gather data on a series of earthquakes that began hitting the area in May. Brian Stump (right) and Chris Hayward, Huffington Department of Earth Sciences, Dedman College, are providing expertise to local and national media outlets for ongoing coverage, including the following stories:

Ruben Habito, World Religions, Perkins School of Theology, talks about the increasing acceptance of Buddhism among Christians and Jews who infuse Eastern spiritual insights and practices into their own religions with The Denver Post Aug. 9, 2009.

Kathy Hargrove, Gifted Students Institute, Annette Caldwell Simmons School of Education and Human Development, spoke about the need for specialized training for teachers of the gifted and talented with The Dallas Morning News Aug. 9, 2009.

Al Armendariz, Environmental and Civil Engineering, Lyle School of Engineering, discussed air quality problems in Denton County with The Denton Record-Chronicle Aug. 2, 2009. In addition, he wrote an op-ed on the failure of the North Texas clean-air plan and its consequences for The Dallas Morning News, published July 13, 2009.

Jeff Talley (at right in photo, with Gen. David Petraeus), Environmental and Civil Engineering, Lyle School of Engineering, was the subject of a feature detailing his ideas for using engineering to fight global poverty. It appeared in The Fort Worth Star-Telegram July 29, 2009.

Tom Mayo, Maguire Center for Ethics and Public Responsibility, provided expertise for a story on health care rationing and the author’s 91-year-old father that appeared in Politics Daily July 29, 2009.

William Maxwell, Finance, Cox School of Business, talked about the state of the American auto industry with The Dallas Morning News July 13, 2009.

John Attanasio, Dean, Dedman School of Law, discussed why Dallas’ law practices have managed to avoid the downsizing occurring at many large national practices with The Dallas Morning News July 6, 2009.

Darab Ganji and Robert Jordan, Tower Center for Political Studies, Dedman College, wrote an op-ed on the post-election uprising in Iran that was published in The Dallas Morning News June 22, 2009.

Fred Schmidt, Christian Spirituality, Perkins School of Theology, discussed the June 2009 meeting of representatives from Episcopal congregations and dioceses to create a new denomination for a story published by The Fort Worth Star-Telegram June 22, 2009.

Glenn Griffin, Advertising, Meadows School of the Arts, discussed the advantages and drawbacks of the state opening its new “Don’t Mess With Texas” video contest to the public with The Dallas Morning News June 17, 2009